The present invention relates to handles for hand tools and more particularly relates to an impact cushioning, molded plastic handle grip that reduces the impact transferred to the hand of a user when the hand tool impacts a work piece.
Many tool handles, such as hammer handles, are constructed of a metal, a synthetic or a composite material. Steel and fiberglass, for example, are often used for tool handle construction. These materials offer reduced materials cost, uniformity of structure and the ability to securely and permanently affix the hammer head or other tool head to the handle. Metal, synthetic and composite handles are relatively durable as compared to wooden handles. Metal, synthetic and composite handles have some disadvantages, however. These handles tend to transfer an undesirable degree of kinetic energy to a user""s hand when a work piece is impacted. Many hammers with metal or synthetic handles are provided with rubber or rubber-like sleeves at the free end opposite the hammer head to provide a degree of impact protection for the hand of the user. Most of these sleeves are constructed of a relatively hard, non-cushioned single material, however, and provide insufficient protection. A need exists for an impact tool grip that can be used on metal, composite and synthetic handles that provides a high degree of cushioning to protect the hand from the kinetic energy transferred thereto during impact and that can be applied to these handles easily during the manufacturing process.
It is an object of the present invention to meet the need expressed above by providing a manually operable impact tool that includes an elongated rigid interior handle structure extending longitudinally with respect to the tool, an impact head disposed at one longitudinal end portion of the handle structure and an exterior impact cushioning gripping structure affixed to a second longitudinal end portion of the elongated interior handle structure in surrounding relation thereto. The exterior impact cushioning gripping structure is formed of inner and outer layers of molded material. The inner layer is a foamed material that is selected from a group consisting of polyvinyl chloride, polypropylene, and thermoplastic elastomer and is molded in surrounding relation to the elongated interior handle structure. The outer layer is constructed of a solid nonfoamed material that is chemically compatible with the inner layer and is molded in surrounding abutting relation to the inner layer. The chemically compatible material used to form the outer layer is chosen from the same group of materials that is used to form the inner layer, viz., polyvinyl chloride, polypropylene, and thermoplastic elastomer. The outer layer is constructed and arranged to provide an inner surface on the outer layer that chemically compatibly bonds to an outside surface of the inner layer and to provide an exterior surface on the outer layer configured to accommodate a manually gripping hand. The arrangement of the gripping structure is such that when it is gripped by a user and the tool is manually operated to impact the tool head on a work piece, the inner layer of foamed material cushions the impact to the gripping hand of the user.
Preferably, the inner layer is molded to provide a plurality of longitudinally extending, circumferentially spaced grooves on the outside surface thereof and the outer layer is molded to provide a plurality of integral inwardly extending ribs on the inner surface thereof that extend within the grooves and that are compatibly chemically bonded therein. The ribs are constructed and arranged so that when a hand grips the exterior impact cushioning gripping structure, the ribs lend rigidity to the gripping load and provide a measure of control of the compression of the foamed inner layer against the handle structure.
The exterior impact cushioning gripping structure can be used on the handles of a wide range of manually operable impact tools including carpenter""s hammers, axes, sledge hammers, pick axes, hatchets and ball peen hammers. The exterior impact cushioning gripping structure can be used, for example, on a hammer that includes an interior handle structure configured to dampen the vibrations that occur in the handle structure when the impact head impacts a work piece. More specifically, the second end portion of the handle structure may include a pair of vibration receiving elements extending longitudinally away from the one longitudinal first end portion and terminating in spaced relation to one another. The vibration receiving elements define a space therebetween and the inner layer of foamed material is formed around the second end portion so that a portion of the inner layer is received within the space and surrounds the vibration receiving elements. Vibrations resulting when the impacting head impacts a work piece are received by the vibration receiving elements and are damped by cooperation between the elements and the inner layer of material to thereby reduce the vibrations that are transmitted to the hand of the user when the impact tool impacts a work piece.